I have a friend with two very young sick kids. Not sure if you can use these for a whole classroom or not but here are some new-to-me sites if you or parents you know have sick kids home for a long time. My mom used to have what she called a rainy day box of toys or activities that we could only play with on a rainy days when we couldn't go outside. Prayer is good but consider care packages for sick families - not just a meal. Include simple crafts, games or ideas for kids who have to stay in bed.
Consider creating rainy day boxes or sick-for-a-week boxes (get-well- soon- boxes?) as a pre-flu season teen, college, parent or grandparent group activity. Parents can plan ahead. It gives other life-stage groups opportunity to think about people in a different life stage than their own. Life stage groups tend to be more"us" centered than outwardly relational. Not everyone is a parent but most of us were sick kids once.
Here are some websites. There are lots of children's magazine websites and parent magazine websites with craft and game ideas. You may even find some with specific ideas for sick kids. You may also find local sites with ideas and activities (Rochester's Kids Out and About)
[You already know Kidology has oodles of games and activities for children's ministry!]
Highlights for Kids
Pockets (Upper Room) has print and play games. (paper pencil games),
Print-N-Play toys - (notice that there are restrictions.)
Pencil Paper Games for older kids
paper pencil games. This site has a game called Sprouts I haven't seen before.
print and play games. This one is fun!
There are also puzzle maker sites to create cross-word puzzles and word games. But you probably already know that.